1. Technical Field
The present invention relates to a method of manufacturing a film member and a film target for laser-driven ion acceleration, and methods of manufacturing the same. More particularly, in order to accelerate ions (including protons) by focusing of high power laser beams, a film member which has a thickness ranging from several nanometers to 1 mm is used, and only a film member exists at the laser focusing point on a film target. The present invention also relates to a film target for laser-driven ion acceleration and a method of manufacturing the same, with which alignment of the target with respect to laser may be done by simply shifting either target or laser and/or both on a two-dimensional plane, instead of a complicated alignment process every time, so that ion acceleration from a film member through focusing of laser beams can be repeated several times.
2. Description of the Related Art
When high power laser beams having an output power of several terawatts (trillion watts) are focused on a thin target with a small focal spot, the target is ionized to generate plasma, and electrons in plasma are heated by the laser light, thereby generating high energy electrons.
The high energy electrons are separated from ions in plasma and escape from the target, so that an intense electrostatic field is generated on the target. The intense electrostatic field then accelerates materials constituting the target or ions contained in a contamination layer existing on the surface of the target. Such an ion acceleration process is referred to as laser-driven ion acceleration.
Recent research shows that focusing of laser beams having an output of several hundred terawatts to several petawatts (1000 trillion watts) on a target with a nanometer scale thickness results in generation of protons with a GeV level energy.
Conventionally, a metal (aluminum, gold, silver, or the like) and non-metal (Mylar, polypropylene, or the like) film target having a thickness ranging from several nanometers to several tens of micrometers has been used. However, with such materials, it is difficult to manufacture a film target having a thickness of several nanometers, and such a film target requires a complicated manufacturing process. Moreover, manufacture of a film target having wide area can be difficult according to materials.